Probabilities also can be derived mathematically. For example, seismologists estimate the number of years it could take to experience an earthquake of a certain magnitude by accounting for two processes:.
Earthquake forecasts provide information on the likelihood of earthquakes over a shorter time window of time. Forecasts are used typically to describe aftershocks , which tend to follow a pattern of decreasing frequency and magnitude over time after an earthquake. However, despite considerable research effort, scientists are only capable of making estimates about where big quakes are most likely to happen in the long term years to decades.
There is yet no reliable way of predicting in the short term days to weeks or months when an earthquake of a given size will occur in a specific location. More than , earthquakes are recorded globally each year. Global, regional, and local seismic monitoring provides information to understand earthquake occurrence and thus map regions of high and low seismic hazard.
Dense seismic monitoring and advanced seismic analysis techniques have facilitated the discovery of so far unknown seismic phenomena slow-slip events, multiple re-rupturing of faults, super-sonic rupture speed , which shed light onto the physics of earthquakes. Continuous seismic monitoring thus provides fundamental information for seismic hazard assessment and earthquake engineering. Prev NEXT. Forces of Nature. Natural Disasters.
Why do earthquakes cause tsunamis? Cite This! Print Citation. Try Our Crossword Puzzle! What Is the Missing Number? Try Our Sudoku Puzzles! Construction is a large factor in what happens during an earthquake. For example, many more people died in the Armenia earthquake where people live in mud houses than in the earthquake in Loma Prieta. The key to earthquake safety are the structures we live in. But the reason why not all buildings are not built to withstand earthquakes is cost.
More sturdy structures are much more expensive to build, so communities must weigh how great the hazard is, what different building strategies cost, and make an informed decision. But this is the crucial factor in earthquake safety. When Salt Lake City has its expected 7. But on January 12, , Haiti experienced a 7.
The difference—building codes. Skyscrapers and other large structures built on soft ground must be anchored to bedrock, even if it lies hundreds of meters below the ground surface. Larger buildings must sway, but not so much that they touch nearby buildings. Counterweights and diagonal steel beams are used to hold down sway.
Large buildings can also be placed on rollers so that they move with the ground. Earthquake prone areas should have building codes that require the use of correct building materials.
Houses should also be built with wood and steel rather than brick and stone because they need to be able to bend and sway. New buildings should be built on layers of steel and rubber to absorb the shock of the waves. Connections, such as where the walls meet the foundation, must be made strong to withstand the shaking. In a multi-story building, the first story must be well supported. Elevated freeways and bridges can also be retrofitted so that they do not collapse.
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